Many people will have headed into the new year resolved to lose some weight and, hopefully, keep off the weight they manage to shed. Green tea preparations are used by some to help both these efforts, but their effectiveness is unclear. To address this uncertainty, a new Cochrane review has been conducted to bring together the evidence from randomised controlled trials (RCTs) looking at the use of green tea preparations by overweight or obese adults. Previous systematic reviews on this topic have been inconclusive.
The review team conducted the usual extensive searches which characterise Cochrane reviews and did not impose any language restrictions. Importantly, the chemical content of the tea preparations in each study was considered, as this is something that varies considerably. RCTs were only included if they used a preparation containing green tea alone and the chemical composition specified and compared this with a placebo or active weight-loss medication where it was possible to conceal from study participants which preparation they were taking. Trials had to last at least 12 weeks.
18 RCTs were included with over 2000 participants. 15 were concerned with weight loss and three with weight maintenance. Here’s what they found:
- Green tea was associated with small reductions in weight loss which were not statistically significant and unlikely to be clinically significant
- Green tea had no significant effect on weight maintenance
- No studies reported on mortality or health-related quality of life, outcomes which the reviewers hoped to explore
- Study quality was judged to be reasonable overall, but many studies had some methodological problems and information on adverse effects and compliance were poorly reported
- There was a lot of variety between studies, including in the tea preparations and the lowest body mass index (BMI) considered to be overweight
So there you have it, enjoy your green tea but don’t expect it to help with your weight. Disappointing. How are you doing with those resolutions to exercise more, something we know is so important for everyone’s health? There’ll be plenty of blogs on that topic here at the Lifestyle Elf and in the next blog we’ll be looking at the benefits of Nordic walking.
Links:
Jurgens TM, Whelan AM, Killian L, Doucette S, Kirk S, Foy E. Green tea for weight loss and weight maintenance in overweight or obese adults. Cochrane Database of Systematic Reviews 2012, Issue 12. Art. No.: CD008650. DOI: 10.1002/14651858.CD008650.pub2.
Cochrane summary of this review.